security: restrict MinIO app to one bucket

apps/api/tests/test_readiness.py

@@ -11,12 +11,13 @@ from app.readiness import readiness_report
 
 
 class AvailableStorage:
-    def list_buckets(self) -> dict[str, list[object]]:
-        return {"Buckets": []}
+    def head_bucket(self, *, Bucket: str) -> dict[str, object]:
+        assert Bucket
+        return {}
 
 
 class UnavailableStorage:
-    def list_buckets(self) -> None:
+    def head_bucket(self, *, Bucket: str) -> None:
         raise ConnectionError("fixture unavailable")